1. Field of the Invention
The present invention relates to a light sensitive apparatus including a non-single crystal semiconductor. More particularly, the present invention relates to a light sensitive apparatus including a light sensitive body comprising a light transmissible substrate and a thin film of non-single crystal semiconductor layer deposited on a major surface of the substrate, and at least two lead members electrically connected to the light sensitive body.
2. Description of the Prior Art
Demand of a light sensitive apparatus for electrically detecting light, that is, a so-called light sensor, has been increased in various fields as the usage or utilization of an optoelectronics technique increases more and more.
FIG. 1 is a front view of a conventional light sensitive apparatus and FIG. 2 is a cross-sectional view taken along a line A-A' in FIG. 1. Such a conventional light sensitive apparatus comprises a semiconductor substrate 1 comprised of a single crystal silicon having a PN junction 2, a coating film 3 of silicon dioxide (SiO.sub.2) formed on a major surface of the semiconductor substrate 1 by a oxidation process, a surface electrode 4 formed of aluminium (Al) and the like coupled to a region of one conductivity type through the coating film 3, and a bottom surface electrode 5 formed of gold (Au) and the like contacted in an ohmic contact manner with a region of an opposite conductivity type in the other major surface of the semiconductor substrate 1, so that a light sensitive body 6 of a so-called photodiode is formed. A first lead member 7 comprised of a lead frame comprises a flag-like portion 7a in the upper portion thereof, as shown in FIG. 3. The light sensitive body 6 is disposed on and fixed to the flag-like portion 7a so that the first lead member 7 is electrically connected to the bottom surface electrode 5. On the other hand, a second lead member 8 comprised of a lead frame is electrically connected to the surface electrode 4 through a wire lead 9 of Au and the like. The connection of the light sensitive body 6 with the two lead bodies 7 and 8 including the wire lead 9 are surrounded and protected by a mold body 10 comprised of a transparent epoxy resin which can transmit light. The mold body 10 is formed in a predetermined shape by a transfer mold process since the mold body 10 needs a uniform light transmission characteristic.
However, since the surface electrode 3 in such a light sensitive apparatus is electrically connected to the second lead member 8 through a fine wire lead 9, an efficiency for operation is very low and, in addition, there has been a danger that the fine wire lead 9 may be disconnected due to pressurized insertion of the resin in transfer-molding the mold body 10. Further, in order to enable the mold body 10 to transmit light which is to be applied to the PN junction 2 in the light sensitive body 6, an incident surface of the mold body 10 must be processed to become a mirror surface.
Japanese Patent Publication No. 33868/1981 (Japanese Patent Application No. 23361/1979) discloses a structure of a photovoltaic device wherein a sintering layer of cadmium sulfide and a sintering layer of cadmium telluride are stacked in this order, and a first electrode is disposed on the sintering layer of cadmium telluride and a second electrode is disposed on the sintering layer of cadmium sulfide, each of the first and second electrodes being connected to a wire lead. In accordance with this structure of a photovoltaic device, since the sintering layers are used as a semiconductor layer, the respective thickness of the layers can not be made in a micron order. Therefore, there is a significant level difference between two electrodes, the level difference adversely affecting a strength for supporting the photovoltaic device by a lead wire. It should be desirable to reduce such level difference.